A two-degree-of-freedom rotation device and its application system are commonly used for achieving a stable platform and an automatically levelling device and so on, and are cores for achieving a driving and stabilizing device and method with three rotational degrees of freedom.
At present, the two-degree-of-freedom rotating device is mostly realized by two mutually orthogonal rotating gimbal frames. A motor and a sensor are respectively mounted at two ends of a rotating shaft of each of the gimbal frames, to achieve driving and rotation angle measurement. The exterior of the two-degree-of-freedom rotating device is supported and fixed with a frame.
Reference is made to FIG. 1 which is a schematic view showing the structure of a gimbal-type two-degree-of-freedom rotation control device.
As shown in the figure, two rectangular rotating gimbal frames 1′ (spherical gimbal frames may also be used) are orthogonal to each other, and a driving motor 2′ and an angle sensor 3′ are respectively provided at two ends of each of two rotating drive shafts of the rotating gimbal frames 1′. The two rotating shafts are controlled and adjusted according to measurement data of the angle sensors 3′, thereby achieving stable control of a stabilization platform 4′. The driving motor 2′ is a conventional electromagnetic induction motor.
Since the two rotating shafts are required to be perpendicular and orthogonal to each other and the driving motors are required to be mounted at ends of the two shafts, this two-degree-of-freedom rotation control device has the following disadvantages.
Firstly, the gimbal frame form and the nested structure may cause the entire device to have a too large volume, which is not good for miniaturization of the entire device, causes the entire device to take up too much space and causes great difficulties in arrangement and assembly.
Secondly, although the two-degree-of-freedom rotation control device has a simple structure when viewed from the principle diagram, in actual manufacturing process, in order to ensure the two rotating shafts to be precisely perpendicular and orthogonal to each other, the mechanical structure of the two-degree-of-freedom rotation control device may be very complex and has very high precision requirements in processing, assembling and adjusting processes, which causes the device to have a high cost.
Thirdly, the gimbal frame structure causes the entire device to have a poor rigidity and an unstable performance.